[HOTFIX] [BUILD] Fix MiMa checks in master branch; enable MiMa for la…

…uncher project

This commit changes the MiMa tests to test against the released 1.4.0 artifacts rather than 1.4.0-rc4; this change is necessary to fix a Jenkins build break since it seems that the RC4 snapshot is no longer available via Maven.

I also enabled MiMa checks for the `launcher` subproject, which we should have done right after 1.4.0 was released.

Author: Josh Rosen <joshrosen@databricks.com>

Closes apache#6974 from JoshRosen/mima-hotfix and squashes the following commits:

4b4175a [Josh Rosen] [HOTFIX] [BUILD] Fix MiMa checks in master branch; enable MiMa for launcher project

project/MimaBuild.scala

@@ -91,8 +91,7 @@ object MimaBuild {
 
   def mimaSettings(sparkHome: File, projectRef: ProjectRef) = {
     val organization = "org.apache.spark"
-    // TODO: Change this once Spark 1.4.0 is released
-    val previousSparkVersion = "1.4.0-rc4"
+    val previousSparkVersion = "1.4.0"
     val fullId = "spark-" + projectRef.project + "_2.10"
     mimaDefaultSettings ++
     Seq(previousArtifact := Some(organization % fullId % previousSparkVersion),

project/SparkBuild.scala

@@ -166,9 +166,8 @@ object SparkBuild extends PomBuild {
   /* Enable tests settings for all projects except examples, assembly and tools */
   (allProjects ++ optionallyEnabledProjects).foreach(enable(TestSettings.settings))
 
-  // TODO: remove launcher from this list after 1.4.0
   allProjects.filterNot(x => Seq(spark, hive, hiveThriftServer, catalyst, repl,
-    networkCommon, networkShuffle, networkYarn, launcher, unsafe).contains(x)).foreach {
+    networkCommon, networkShuffle, networkYarn, unsafe).contains(x)).foreach {
       x => enable(MimaBuild.mimaSettings(sparkHome, x))(x)
     }